Network node and method for indicating to wireless device that system information (si) has changed for purposes of a system access procedure

ABSTRACT

A network node (e.g., base station, eNodeB) is described herein which indicates that System Information (SI) has changed in at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block, and transmits the at least one of the FCCH block or the SCH block to at least one wireless device. In addition, a wireless device is described herein which receives the at least one of a FCCH block or the SCH block, and determines if the received at least one of the FCCH block or the SCH block indicates that SI has changed and uses this information for purposes of a system access procedure.

CLAIM OF PRIORITY

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/040,154, filed on Aug. 21, 2014, the entire contentsof which are hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to a network node (e.g., base station,eNodeB) which indicates that System Information (SI) has changed in atleast one of a frequency correction channel (FCCH) block or asynchronization channel (SCH) block, and transmits the at least one ofthe FCCH block or the SCH block to at least one wireless device. Inaddition, the present disclosure relates to a wireless device whichreceives the at least one of a FCCH block or the SCH block, anddetermines if the received at least one of the FCCH block or the SCHblock indicates that SI has changed and uses this information forpurposes of a system access procedure.

BACKGROUND

The following abbreviations and terms are herewith defined, at leastsome of which are referred to within the following description of thepresent disclosure.

-   -   3GPP 3rd-Generation Partnership Project    -   ASIC Application Specific Integrated Circuit    -   BCCH Broadcast Control Channel    -   DSP Digital Signal Processor    -   EDGE Enhanced Data rates for GSM Evolution    -   EGPRS Enhanced General Packet Radio Service    -   FCCH Frequency Correction Channel    -   GMSK Gaussian Minimum Shift Keying    -   GSM Global System for Mobile Communications    -   HARQ Hybrid Automatic Repeat Request    -   IoT Internet of Things    -   LTE Long-Term Evolution    -   M2M Machine-to-Machine    -   MCS Modulation and Coding Scheme    -   MS Mobile Station    -   MTC Machine-Type Communications    -   SCH Synchronization Channel    -   SI System Information    -   UE User Equipment    -   UL Uplink    -   WCDMA Wideband Code Division Multiple Access    -   WiMAX Worldwide Interoperability for Microwave Access

Extended Coverage: The general principle of extended coverage is that ofusing blind repetitions for the control channels and for the datachannels. In addition, for the data channels the use of blindrepetitions assuming MCS-1 (i.e., the lowest MCS supported in EGPRStoday) is combined with HARQ retransmissions to realize the needed levelof data transmission performance. Support for extended coverage isrealized by defining different coverage classes. A different number ofblind repetitions are associated with each of the coverage classeswherein extended coverage is associated with coverage classes for whichmultiple blind repetitions are needed (i.e., a single blind repetitionis considered as the reference coverage). The number of total blindtransmissions for a given coverage class can differ between differentlogical channels.

System Access Procedure: The steps performed by a wireless device toverify if System Information needs to be reacquired, reacquire SystemInformation if necessary, notify a network node that the network nodeneeds to transmit information (e.g., application layer payload) andreceive from the network node an assignment of radio resources to beused by the wireless device to transmit that information.

System Information: The set of parameters sent by a network node on abroadcast control channel (BCCH) used by a wireless device to determineradio related parameters to be applied when attempting system access tothe network node on the random access channel (RACH) of the commoncontrol channel (CCCH) and to determine the availability of neighborcells.

System Information (SI) is information broadcasted by a network node(e.g., base station, eNodeB) in a cell to all wireless devicesmonitoring the specific cell. The reading of the SI by a wirelessdevice, especially when in extended coverage, consumes energy and hencehas a negative impact on a battery life of the wireless device. It istherefore of interest for the wireless device to read the SI asinfrequently as possible. At the same time changes to the SI could bevital and should be communicated to the wireless device before thewireless device performs a system access procedure, by providing forexample information on how the wireless device should access the system.Hence, it is also of interest to, as early as possible, indicate to awireless device that is in the process of initiating a system accessprocedure that the SI has recently changed and therefore needs to bereacquired before performing the system access procedure. Theaforementioned interests and other interests are addressed by thepresent disclosure.

SUMMARY

A network node, a wireless device and various methods are described inthe independent claims. Advantageous embodiments of the network node,the wireless device, and the various methods are further described inthe dependent claims.

In one aspect, the present disclosure provides a network node in awireless communication system. The network node comprises a processingmodule configured to indicate that SI has changed in at least one of aFCCH block or a SCH block. Plus, the network node comprises atransceiver module configured to transmit the at least one of the FCCHblock or the SCH block to at least one wireless device. The network nodehas an advantage in that the network node indicates to a wireless devicethat is in the process of initiating a system access procedure that theSI has recently changed and therefore needs to be reacquired beforeperforming the system access procedure.

In another aspect, the present disclosure provides a method in a networknode of a wireless communication system. The method comprises anindicating step and a transmitting step. In the indicating step, thenetwork node indicates that SI has changed in at least one of a FCCHblock or a SCH block. In the transmitting step, the network nodetransmits the at least one of the FCCH block or the SCH block to atleast one wireless device. The method has an advantage in that itenables the network node to indicate to a wireless device that is in theprocess of initiating a system access procedure that the SI has recentlychanged and therefore needs to be reacquired before performing thesystem access procedure.

In yet another aspect, the present disclosure provides a wireless deviceconfigured to interface with a wireless communication system. Thewireless device comprises a transceiver module configured to receive atleast one of a FCCH block or a SCH block. Plus, the wireless devicecomprises a processing module configured to determine if the received atleast one of the FCCH block or the SCH block indicates that SI haschanged. The wireless device has an advantage in that while the wirelessdevice is in the process of initiating a system access procedure, it candetermine that the SI has recently changed and therefore needs to bereacquired before performing the system access procedure.

In still yet another aspect, the present disclosure provides a method ina wireless device configured to interface with a wireless communicationsystem. The method comprises a receiving step and a determining step. Inthe receiving step, the wireless device receives at least one of a FCCHblock or a SCH block. In the determining step, the wireless devicedetermines if the received at least one of the FCCH block or the SCHblock indicates that SI has changed. The method has an advantage in thatwhile the wireless device is in the process of initiating a systemaccess procedure, the wireless device can determine that the SI hasrecently changed and therefore needs to be reacquired before performingthe system access procedure.

Additional aspects of the invention will be set forth, in part, in thedetailed description, figures and any claims which follow, and in partwill be derived from the detailed description, or can be learned bypractice of the invention. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and are not restrictive of the inventionas disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be obtainedby reference to the following detailed description when taken inconjunction with the accompanying drawings:

FIG. 1 is a diagram of an exemplary wireless communication network whichincludes a network node (e.g., base station, eNodeB) and a wirelessdevice, each of which are configured in accordance with an embodiment ofthe present disclosure;

FIG. 2 is a flowchart of a method implemented in the network node (e.g.,base station, eNodeB) in accordance with an embodiment of the presentdisclosure;

FIG. 3 is a block diagram illustrating structures of an exemplarynetwork node (e.g., base station, eNodeB) configured in accordance withan embodiment of the present disclosure;

FIG. 4 is a flowchart of a method implemented in a wireless device inaccordance with an embodiment of the present disclosure;

FIG. 5 is a block diagram illustrating structures of an exemplarywireless device configured in accordance with an embodiment of thepresent disclosure;

FIG. 6 is a flowchart of a method which is implemented by the wirelessdevice in accordance with an embodiment of the present disclosure; and,

FIG. 7 is a flowchart of a method which is implemented by the wirelessdevice in accordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION

As discussed in the Background section, it is of interest for a wirelessdevice to read the SI as infrequently as possible. In addition, it is ofinterest to indicate as early as possible to a wireless device that isin the process of initiating a system access procedure that the SI hasrecently changed and therefore needs to be reacquired before performingthe system access procedure. The present disclosure as discussed belowaddresses these interests and in particular the interest related toindicating as early as possible to a wireless device that is in theprocess of initiating a system access procedure that the SI has recentlychanged and therefore needs to be reacquired before performing thesystem access procedure.

Referring to FIG. 1, there is illustrated an exemplary wirelesscommunication network 101 which includes a network node 100 (e.g., basestation 100, eNodeB 100) and a wireless device 110, each of which areconfigured in accordance with an embodiment of the present disclosure.As shown, the network node 100 (e.g., base station, eNodeB) includes (1)a processing module 102 configured to indicate that SI has changed in atleast one of a FCCH block 104 or a SCH block 106, and (2) a transceivermodule 108 configured to transmit the at least one of the FCCH block 104or the SCH block 106 to at least one wireless device 110 (only oneshown) (as illustrated in FIGS. 2-3). The wireless device 110 includes(1) a transceiver module 114 configured to receive the at least one ofthe FCCH block 104 or the SCH block 106, and (2) a processing module 112configured to (i) determine if the received at least one of the FCCHblock 104 or the SCH block 106 indicates that SI has changed, (ii) whenthe SI has changed then read SI as part of a system access procedure,(iii) when the SI has not changed then determine if a last reading of SIis still valid, and when it is determined that the last reading of SI isstill valid then continue a system access procedure without reading SI,and when it is determined that the last reading of SI is not still validthen read SI as part of a system access procedure (as illustrated inFIGS. 4-5).

Referring to FIG. 2, there is a flowchart of a method 200 implemented inthe network node 100 (e.g., base station 100, eNodeB 100) in accordancewith an embodiment of the present disclosure. At step 202, the networknode 100 indicates that the SI has changed in the at least one of theFCCH block 104 or the SCH block 106. In one example, the network node100 at step 202 a indicates that the SI has changed in the FCCH block104 by shifting a frequency offset relative to a carrier centerfrequency to a level (amount) detectable by the at least one wirelessdevice 110. For instance, the network node 100 can shift the frequencyoffset relative to the carrier center frequency to the level (amount)detectable by the at least one wireless device 110 to indicate that theSI has changed by one of the following: (i) using a negative modulationindex for GMSK modulation, (ii) using an alternative (i.e., alternating)fixed bit pattern (it is to be noted that the conventional network nodefeeds its modulator with a stream of bits having form “0000000 . . . ”to create a tone at +67 kHz offset, while in the present disclosure thenetwork node 100 can feed its modulator with a stream of bits havingform of “0101010101 . . . ” to create a tone at −67 kHz offset), or(iii) using some other measure. In another example, the network node 100at step 202 b uses a flag in the SCH block 106 to indicate that the SIhas changed. At step 204, the network node 100 transmits the at leastone of the FCCH block 104 or the SCH block 106 to the at least onewireless device 110. A more detailed explanation of this method 200along with various alternative exemplary methods 600 and 700 associatedwith the present disclosure are discussed hereinafter.

Referring to FIG. 3, there is a block diagram illustrating structures ofan exemplary network node 100 (e.g., base station 100, eNodeB 100)configured in accordance with an embodiment of the present disclosure.In one embodiment, the network node 100 may comprise an indicationmodule 302 and a transmit module 304. The indication module 302 isconfigured to indicate that the SI has changed in the at least one ofthe FCCH block 104 or the SCH block 106. In one example, the indicationmodule 302 indicates that the SI has changed in the FCCH block 104 byshifting a frequency offset relative to a carrier center frequency to alevel (amount) detectable by the at least one wireless device 110. Forinstance, the indication module 302 can shift the frequency offsetrelative to the carrier center frequency to the level (amount)detectable by the at least one wireless device 110 to indicate that theSI has changed by one of the following: (i) using a negative modulationindex for GMSK modulation, (ii) using an alternative (i.e., alternating)fixed bit pattern (it is to be noted that the conventional network nodefeeds its modulator with a stream of bits having form “0000000 . . . ”to create a tone at +67 kHz offset, while in the present disclosure thenetwork node 100 can feed its modulator with a stream of bits havingform of “0101010101 . . . ” to create a tone at −67 kHz offset), or(iii) using some other measure. In another example, the indicationmodule 302 uses a flag in the SCH block 106 to indicate that the SI haschanged. The transmit module 304 is configured to transmit the at leastone of the FCCH block 104 or the SCH block 106 to the at least onewireless device 110.

As those skilled in the art will appreciate, the above-described modules302 and 304 of the network node 100 may be implemented separately assuitable dedicated circuits. Further, the modules 302 and 304 can alsobe implemented using any number of dedicated circuits through functionalcombination or separation. In some embodiments, the modules 302 and 304may be even combined in a single application specific integrated circuit(ASIC). As an alternative software-based implementation, the networknode 100 may comprise the processing module 102 which includes a memory,and a processor (including but not limited to a microprocessor, amicrocontroller or a Digital Signal Processor (DSP), etc.), and thetransceiver module 108. The memory stores machine-readable program codeexecutable by the processor to cause the network node 100 to perform thesteps of the above-described method 200. It should be appreciated thatthe network node 100 also includes many other well-known components, butfor clarity, only the components needed to describe the features of thepresent disclosure are described herein.

Referring to FIG. 4, there is a flowchart of a method 400 implemented inthe wireless device 110 in accordance with an embodiment of the presentdisclosure. At step 402, the wireless device 110 receives the at leastone of the FCCH block 104 or the SCH block 106. At step 404, thewireless device 110 determines if the received at least one of the FCCHblock 104 or the SCH block 106 indicates that SI has changed. In oneexample, the wireless device 110 at step 404 a determines if thereceived FCCH block 104 indicates that the SI has changed by detecting ashift of a frequency offset relative to a carrier center frequency inthe received FCCH block 104. In another example, the wireless device 110at step 404 b determines if the received SCH block 106 indicates thatthe SI has changed by reading a flag in the SCH block 106. If the resultof step 404 is a determination of yes, the wireless device 110 at step406 reads SI as part of a system access procedure. If the result of step404 is a determination of no, the wireless device 110 at step 408determines if a last reading of SI is still valid. If the result of step408 is a determination of yes, the wireless device 110 at step 410continues a system access procedure without reading SI. If the result ofstep 408 is a determination of no, the wireless device 110 at step 412reads SI as part of a system access procedure. A more detailedexplanation of this method 400 along with various alternative exemplarymethods 600 and 700 associated with the present disclosure are discussedhereinafter.

Referring to FIG. 5, there is a block diagram illustrating structures ofan exemplary wireless device 110 configured in accordance with anembodiment of the present disclosure. In one embodiment, the wirelessdevice 110 may comprise a receive module 502, a first determine module504, a first read module 506, a second determine module 508, a continuemodule 510, and a second read module 512. The receive module 502 isconfigured to receive the at least one of the FCCH block 104 or the SCHblock 106. The first determine module 504 is configured to determine ifthe received at least one of the FCCH block 104 or the SCH block 106indicates that SI has changed. In one example, the first determinemodule 504 is configured to determine if the received FCCH block 104indicates that the SI has changed by detecting a shift of a frequencyoffset relative to a carrier center frequency in the received FCCH block104. In another example, the first determine module 504 is configured todetermine if the received SCH block 106 indicates that the SI haschanged by reading a flag in the SCH block 106. The first read module506 is configured to read SI as part of a system access procedure if thereceived at least one of the FCCH block 104 or the SCH block 106indicates that SI has changed. The second determine module 508 isconfigured to determine if a last reading of SI is still valid if thereceived at least one of the FCCH block 104 or the SCH block 106indicates that the SI has not changed. The continue module 510 isconfigured to continue a system access procedure without reading SI ifthe last reading of SI is determined to still be valid. The second readmodule 512 is configured to read SI as part of a system access procedureif the last reading of SI is determined to not be still valid.

As those skilled in the art will appreciate, the above-described modules502, 504, 506, 508, 510 and 512 of the wireless device 110 may beimplemented separately as suitable dedicated circuits. Further, themodules 502, 504, 506, 508, 510 and 512 can also be implemented usingany number of dedicated circuits through functional combination orseparation. In some embodiments, the modules 502, 504, 506, 508, 510 and512 may be even combined in a single application specific integratedcircuit (ASIC). As an alternative software-based implementation, thewireless device 110 may comprise the processing module 112 whichincludes a memory, and a processor (including but not limited to amicroprocessor, a microcontroller or a Digital Signal Processor (DSP),etc.), and the transceiver module 114. The memory storesmachine-readable program code executable by the processor to cause thewireless device 110 to perform the steps of the above-described method400. It should be appreciated that the wireless device 110 also includesmany other well-known components, but for clarity, only the componentsneeded to describe the features of the present disclosure are describedherein.

Further, it should be appreciated that the wireless device 110 may refergenerally to an end terminal (user) that attaches to the wirelesscommunication network, and may refer to either an M2M device or MTCdevice (e.g., smart meter) or a non-M2M/MTC device. Thus, the term maybe synonymous with the term mobile device, mobile station (MS), “UserEquipment” or UE, as that term is used by the 3rd-Generation PartnershipProject (3GPP), and includes standalone wireless devices, such asterminals, IoT devices, cell phones, tablets, smart phones, andwireless-equipped personal digital assistants, as well as wireless cardsor modules that are designed for attachment to or insertion into anotherelectronic device, such as a personal computer, electrical meter, etc.

The following is a detailed explanation of various technical featuresand various alternative exemplary methods 600 and 700 associated withthe present disclosure. As discussed above, a flag is included in theSCH block 106 indicating that the SI has recently changed, which impliesto the wireless device 110 that the wireless device's system accessprocedure is to also include the reading of SI. If the flag in the SCHblock 106 is not set, and the previous reading of SI is still valid(according to some minimum allowed periodicity of reacquiring SI), thereading of SI need not be part of the system access procedure of thewireless device 110. It should be appreciated that the SCH block 106 isalso used by wireless devices 110 to synchronize to the cell in bothtime and frequency. Plus, the SCH block 106 also includes informationrelating to the frame number and base station identity. Further, theindication where the SI has changed could also be provided in the FCCHblock 104 rather than or in addition to the SCH block 106. The FCCHblock 104 can be used to indicate that the SI has changed by using, forexample, a negative modulation index for the GMSK modulation, analternative (i.e., alternating) fixed bit pattern or other measures thatshift the offset to a level (amount) detectable by the device, e.g.,−67.7 kHz. It should also be appreciated that the FCCH block 104 is alsoused by wireless devices 110 to synchronize in frequency to a cell, andhence if an alternative frequency is used by the FCCH, the wirelessdevice 110 will use the alternative frequency to synchronize to a cell.The current FCCH block 104 includes a single burst block consisting of142 fixed bits modulated with GMSK which is equivalent to an unmodulatedcarrier, shifted in frequency by a 67.7 kHz frequency offset whencompared to the GSM/EDGE channel center frequency.

Further, considering that different wireless devices 110 will access thesystem (i.e., network node 110) in different ways (some periodic, somemore random, some with different inter-access time intervals), a set ofpredetermined rules could be used by the network node 100 and wirelessdevice 110 to allow for a clear interpretation of the intention of theflag indicating the modification of SI. Such predetermined rules couldinclude, but are not limited to:

-   -   a. The network node 100 is only allowed to modify the System        Information content no more often than once every X seconds and        therefore needs to keep the value of the flag (and System        Information content) unchanged for X seconds following any given        instance of changing the flag value (and content of System        Information).    -   b. If a wireless device 100 wakes up and determines that the        System Information has changed (e.g., the value of the flag has        toggled since SI was last read or the amount of time since the        wireless device's last system access attempt exceeds Y seconds),        then the wireless device shall reacquire System Information.

Referring to FIG. 6, there is a flowchart of a method 600 which isimplemented by the wireless device 110 in accordance with an embodimentof the present disclosure (it is to be noted that this method 600 can bereferred to as “Simple Boolean flag on SCH indicating a modification ofSI content”). At step 602, the wireless device 110 determines that asignal strength is high enough to synchronize to a cell. At step 604,the wireless device 110 reads the FCCH block 104 to provide a roughfrequency and time synchronization in the cell. At step 606, thewireless device 110 reads the SCH block 106 to provide a fine frequencyand time synchronization in the cell. At step 608, the wireless device110 reads the flag in the SCH block 106 indicating if the SI haschanged. At step 610, the wireless device 110 determines if the SI haschanged by determining if the flag is set. If the result of step 610 isa determination of yes, then the wireless device 110 at step 612 readsthe SI as part of the system access procedure. If the result of step 610is a determination of no, then the wireless device 110 at step 614determines if a last reading of SI is still valid. If the result of step614 is a determination of yes, the wireless device 110 at step 616continues a system access procedure without reading SI. If the result ofstep 614 is a determination of no, the wireless device 110 at step 618reads SI as part of a system access procedure.

Referring to FIG. 7, there is a flowchart of a method 700 implemented bythe wireless device 110 in accordance with an embodiment of the presentdisclosure (it is to be noted that this method can be referred to as“Simple Boolean flag on FCCH indicating a modification of SI content”).At step 702, the wireless device 110 determines that a signal strengthis high enough to synchronize to a cell. At step 704, the wirelessdevice 110 reads the FCCH block 104. At step 706, the wireless device110 determines if the FCCH block 104 is rotated with −π/2 (90 degrees)(equivalent as placed +67.7 kHz or −67.7 kHz relative to carrier centerfrequency). If the result of step 706 is a determination of yes, thenthe wireless device 110 knows that the SI has changed and at step 708reads the SI as part of the system access procedure. If the result ofstep 706 is a determination of no, then the wireless device 110 knowsthat the SI has not changed and at step 710 determines if a last readingof SI is still valid. If the result of step 710 is a determination ofyes, the wireless device 110 at step 712 continues a system accessprocedure without reading SI. If the result of step 710 is adetermination of no, the wireless device 110 at step 714 reads SI aspart of a system access procedure.

In the foregoing description, numerous specific details are set forth.However, it is understood that embodiments of the present disclosure maybe practiced without these specific details. In other instances,well-known circuits, structures and techniques have not been shown indetail in order not to obscure the understanding of this description.Those of ordinary skill in the art, with the included descriptions, willbe able to implement appropriate functionality without undueexperimentation. Plus, it should be appreciated that although thefeatures in the present disclosure are exemplified in GSM/EDGE, othertypes of wireless communication systems may be able to similarly employthe functionality described herein including, for example, UTRAN, WCDMA,LTE, and WiMAX systems.

Further it should be noted that references in the specification to “oneembodiment,” “an embodiment,” “an example embodiment,” etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to implement suchfeature, structure, or characteristic in connection with otherembodiments whether or not explicitly described.

Those skilled in the art will appreciate that the use of the term“exemplary” is used herein to mean “illustrative,” or “serving as anexample,” and is not intended to imply that a particular embodiment ispreferred over another or that a particular feature is essential.Likewise, the terms “first” and “second,” and similar terms, are usedsimply to distinguish one particular instance of an item or feature fromanother, and do not indicate a particular order or arrangement, unlessthe context clearly indicates otherwise. Further, the term “step,” asused herein, is meant to be synonymous with “operation” or “action.” Anydescription herein of a sequence of steps does not imply that theseoperations must be carried out in a particular order, or even that theseoperations are carried out in any order at all, unless the context orthe details of the described operation clearly indicates otherwise.

Of course, the present disclosure may be carried out in other specificways than those herein set forth without departing from the scope andessential characteristics of the invention. One or more of the specificprocesses discussed above may be carried out in a cellular phone orother communications transceiver comprising one or more appropriatelyconfigured processing circuits, which may in some embodiments beembodied in one or more application-specific integrated circuits(ASICs). In some embodiments, these processing circuits may comprise oneor more microprocessors, microcontrollers, and/or digital signalprocessors programmed with appropriate software and/or firmware to carryout one or more of the operations described above, or variants thereof.In some embodiments, these processing circuits may comprise customizedhardware to carry out one or more of the functions described above. Thepresent embodiments are, therefore, to be considered in all respects asillustrative and not restrictive.

Although multiple embodiments of the present disclosure have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it should be understood that the invention is notlimited to the disclosed embodiments, but instead is also capable ofnumerous rearrangements, modifications and substitutions withoutdeparting from the present disclosure that as has been set forth anddefined within the following claims.

1. A network node in a wireless communication system, the network nodecomprising: a processing module configured to indicate that SystemInformation (SI) has changed in at least one of a frequency correctionchannel (FCCH) block or a synchronization channel (SCH) block; and atransceiver module configured to transmit the at least one of the FCCHblock or the SCH block to at least one wireless device.
 2. The networknode of claim 1, wherein the processing module is configured to indicatethat the SI has changed in the FCCH block by shifting a frequency offsetrelative to a carrier center frequency by an amount detectable by the atleast one wireless device.
 3. The network node of claim 2, wherein theprocessing module is configured to shift the frequency offset relativeto the carrier center frequency by the amount detectable by the at leastone wireless device by one of the following: using a negative modulationindex for Gaussian Minimum Shift Keying (GMSK) modulation; or using analternating fixed bit pattern in the FCCH block.
 4. The network node ofclaim 1, wherein the processing module is configured to indicate thatthe SI has changed by using a flag in the SCH block.
 5. The network nodeof claim 4, wherein the processing module is configured to modify SIcontent no more often than once per a predetermined amount of time andmaintain a value of the flag unchanged for the predetermined amount oftime following a modification of the SI content.
 6. A method in anetwork node of a wireless communication system, the method comprising:indicating that System Information (SI) has changed in at least one of afrequency correction channel (FCCH) block or a synchronization channel(SCH) block; and transmitting the at least one of the FCCH block or theSCH block to at least one wireless device.
 7. The method of claim 6,wherein the step of indicating that the SI has changed in the FCCH blockfurther comprises shifting a frequency offset relative to a carriercenter frequency to an amount detectable by the at least one wirelessdevice.
 8. The method of claim 7, wherein the shifting step furthercomprises one of the following: using a negative modulation index forGaussian Minimum Shift Keying (GMSK) modulation; or using an alternatingfixed bit pattern in the FCCH block.
 9. The method of claim 6, whereinthe step of indicating that the SI has changed further comprises using aflag in the SCH block.
 10. The method of claim 9, further comprising astep of modifying SI content no more often than once per a predeterminedamount of time and a step of maintaining a value of the flag unchangedfor the predetermined amount of time following a modification of the SIcontent.
 11. A wireless device in a wireless communication system, thewireless device comprising: a transceiver module configured to receiveat least one of a frequency correction channel (FCCH) block or asynchronization channel (SCH) block; and a processing module configuredto determine if the received at least one of the FCCH block or the SCHblock indicates that System Information (SI) has changed.
 12. Thewireless device of claim 11, wherein the processing module is configuredto determine if the received FCCH block indicates that the SI haschanged by detecting a shift of a frequency offset relative to a carriercenter frequency in the received FCCH block.
 13. The wireless device ofclaim 11, wherein the processing module is configured to determine ifthe received SCH block indicates that the SI has changed by reading aflag in the SCH block.
 14. The wireless device of claim 11, wherein whenthe SI has changed, the processing module is further configured to readSI as part of a system access procedure.
 15. The wireless device ofclaim 11, wherein when the SI has not changed, the processing module isfurther configured to determine if a last reading of SI is still valid,and when it is determined that the last reading of SI is still valid,the processing module is further configured to continue a system accessprocedure without reading SI, and when it is determined that the lastreading of SI is not still valid, the processing module is furtherconfigured to read SI as part of a system access procedure.
 16. A methodin a wireless device in a wireless communication system, the methodcomprising: receiving at least one of a frequency correction channel(FCCH) block or a synchronization channel (SCH) block; and determiningif the received at least one of the FCCH block or the SCH blockindicates that System Information (SI) has changed.
 17. The method ofclaim 16, wherein the step of determining if the received FCCH blockindicates that the SI has changed comprises detecting a shift of afrequency offset relative to a carrier center frequency in the receivedFCCH block.
 18. The method of claim 16, wherein the step of determiningif the received SCH block indicates that the SI has changed comprisesreading a flag in the SCH block.
 19. The method of claim 16, furthercomprising when the SI has changed, reading SI as part of a systemaccess procedure.
 20. The method of claim 16, further comprising: whenthe SI has not changed, determining if a last reading of SI is stillvalid, and when it is determined that the last reading of SI is stillvalid, continuing a system access procedure without reading SI, and whenit is determined that the last reading of SI is not still valid, readingSI as part of a system access procedure.